JPWO2020154273A5 - - Google Patents

Description

(Related Applications)
This application is a non-provisional patent application that claims priority to U.S. Provisional Patent Application No. 62/795,273, filed January 22, 2019, entitled "Linear Motor," which is incorporated herein by reference.

FIELD OF THEINVENTION
The present invention relates generally to materials testing systems, and more particularly to linear motors for materials testing systems.

Linear motors are typically utilized in material testing systems, where they are known to utilize electricity and magnetism to create a back and forth motion in a moving part that can be coupled to a test specimen. The moving assembly may be "frictionless" in that it may be arranged and configured to operate without sliding or rolling contact between the moving part and the suspension system of the moving part . Flexural suspension structures for driving moving parts are known, such as those described in U.S. Pat. No. 6,405,599. These flexible suspension structures, to which the moving part is directly physically attached, limit the movement of the moving part based on the material properties and bendable nature of the flexural suspension structure, and as the moving part moves from a center position due to electromagnetic forces, the flexural suspension structure exerts increasing resistance on the moving part .

Thus, linear motors having frictionless characteristics, as well as methods of use and assemblies thereof, would be well-accepted in the art.

In one exemplary embodiment, the test apparatus includes a stator assembly, a moving part mechanically coupleable to a test body configured to be moved relative to the stator assembly by operation of a linear motor, and a suspension system configured to facilitate movement of the moving part relative to the stator assembly along a movement axis without physically touching the moving part during movement.

Additionally or alternatively, the suspension system of the test apparatus includes at least one air bushing configured to allow movement of the moving part relative to the suspension system without sliding or rolling contact between the moving part and the suspension system.

Additionally or alternatively, the suspension system of the test apparatus includes a frame body having a first opening extending along a first axis parallel to the axis of motion, at least one air bushing is located within the first opening, and the moving part includes a first air bushing shaft extending into the first opening.

Additionally or alternatively, at least one air bushing of the test apparatus includes a first air bushing located proximate a first end of the first opening and a second air bushing located proximate a second end of the first opening.

Additionally or alternatively, the frame body of the test apparatus includes a second opening extending along a second axis parallel to the movement axis, the movement portion includes a second air bushing shaft extending into the second opening, the second opening includes a third air bushing located proximate a first end of the second opening, and a fourth air bushing located proximate a second end of the second opening.

Additionally or alternatively, at least one air bushing of the test apparatus is positioned within the first opening of the frame body such that some movement is permitted between the air bushing and the frame body.

Additionally or alternatively, at least one air bushing of the test apparatus is removably mounted within the first opening of the frame body with an interference fit.

Additionally or alternatively, at least one air bushing of the test apparatus has a hollow cylindrical shape and the first air bushing shaft is a cylindrical shaft having a radius that is 3 to 5 microns smaller than the inner radius of the at least one air bushing.

Additionally or alternatively, the stator assembly of the test apparatus includes a first coil subassembly and a second coil subassembly, the moving part is located and extends between the first coil subassembly and the second coil subassembly, the moving part includes a magnet frame having a plurality of permanent magnets disposed thereon, the first air bushing shaft extends parallel to the magnet frame, the top end plate and the bottom end plate connect the first and second air bushing shafts to the magnet frame such that a first space extends parallel to the axis of movement between the first air bushing shaft and the magnet frame and a second space extends parallel to the axis of movement between the second air bushing and the magnet frame, and the test apparatus further includes a duct system configured to use air flow through the at least one air bushing in cooling at least one of the first and second coil subassemblies and the coils of the moving part .

Additionally or alternatively, the travel portion of the testing apparatus includes a specimen shaft extending from at least one of the top end plate and the bottom end plate, and the fifth air bushing surrounds the specimen shaft.

In another exemplary embodiment, a linear motor includes a stator assembly configured to receive power, a moving part configured to be proximate to the stator assembly and to move relative to the stator assembly when the stator assembly receives power, and a suspension system configured to facilitate movement of the moving part ions relative to the stator assembly along a movement axis without physically touching the moving part during movement.

Additionally or alternatively, the suspension system of the linear motor includes at least one air bushing configured to allow movement of the moving part relative to the suspension system without sliding or rolling contact between the moving part and the suspension system.

Additionally or alternatively, the suspension system of the linear motor includes a frame body having a first opening extending along a first axis parallel to the axis of motion, at least one air bushing is located within the first opening, and the moving part includes a first air bushing shaft extending within the first opening.

Additionally or alternatively, at least one air bushing of the linear motor includes a first air bushing located proximate a first end of the first opening and a second air bushing located proximate a second end of the first opening.

Additionally or alternatively, the frame body of the linear motor includes a second opening extending along a second axis parallel to the movement axis, the movement portion includes a second air bushing shaft extending into the second opening, the second opening includes a third air bushing located proximate a first end of the second opening and a fourth air bushing located proximate a second end of the second opening.

Additionally or alternatively, at least one air bushing of the linear motor is positioned within the first opening in the frame body such that some movement is permitted between the air bushing and the frame body.

Additionally or alternatively, at least one air bushing of the linear motor is removably mounted within the first opening of the frame body with an interference fit.

Additionally or alternatively, at least one air bushing of the linear motor has a hollow cylindrical shape and the first air bushing shaft is a cylindrical shaft having a radius that is 3 to 5 microns smaller than the inner radius of the at least one air bushing.

Additionally or alternatively, the stator assembly of the linear motor includes a first coil subassembly and a second coil subassembly, the moving part is located and extends between the first coil subassembly and the second coil subassembly, the moving part includes a magnet frame having a plurality of permanent magnets disposed thereon, the first air bushing shaft extends parallel to the magnet frame, the top end plate and the bottom end plate connect the first and second air bushing shafts to the magnet frame such that a first space extends parallel to the movement axis between the first air bushing shaft and the magnet frame and a second space extends parallel to the movement axis between the second air bushing and the magnet frame, and the linear motor further includes a duct system configured to use air flow through the at least one air bushing in cooling at least one of the first and second coil subassemblies and the coils of the moving part .

In another exemplary embodiment, a method includes providing a stator assembly, a moving part proximate to the stator assembly, and a suspension system; receiving power by the stator assembly; moving the moving part back and forth relative to the stator assembly along a movement axis after receiving power by the stator assembly; and supporting the moving part with the suspension system without physically touching the moving part during movement.

In another exemplary embodiment, a test apparatus includes a polyphase linear motor including a stator assembly, a moving part mechanically coupleable to a test body configured to be moved relative to the stator assembly by operation of the polyphase linear motor, and a suspension system configured to support the moving part and control movement of the moving part relative to the stator assembly, the suspension system configured to operate without sliding or rolling contact between the moving part and the suspension system.

Additionally or alternatively, the polyphase linear motor of the test device is a three-phase linear motor.

Additionally or alternatively, the stator assembly of the test apparatus includes a first coil subassembly and a second coil subassembly, the moving portion being positioned and extending between the first coil subassembly and the second coil subassembly, the moving portion having a plurality of permanent magnets disposed thereon.

Additionally or alternatively, the first coil subassembly of the test device is a laminated magnetic core including multiple poles around which multiple vertically arranged windings are wound to create a first coil stack, and the second coil subassembly is a laminated magnetic core including multiple poles around which multiple vertically arranged windings are wound to create a second coil stack.

Additionally or alternatively, the magnetic core of the first coil assembly of the test device includes six poles and six vertically arranged windings, the magnetic core of the second coil assembly includes six poles and six vertically arranged windings, the top and fourth windings of each of the first and second coil stacks are connected to a first phase of a three-phase linear motor, the second and fifth windings of each of the first and second coil stacks are connected to a second phase of the three-phase linear motor, and the third and sixth windings of each of the first and second coil stacks are connected to a third phase of the three-phase linear motor.

Additionally or alternatively, a gap is located between each of the multiple vertically arranged windings of the first and second coil stacks of the testing apparatus, and the material testing apparatus further comprises at least one cooling duct configured to provide cooling air through the gap located between each of the multiple vertically arranged windings of the first and second coil stacks.

Additionally or alternatively, each of the multiple poles of the test fixture includes a coil bobbin having integral cooling fins disposed thereon, the integral cooling fins extending through the windings and into the gaps between the windings.

Additionally or alternatively, the test apparatus further includes a potting material located within each gap, and at least one heat pipe embedded within the potting material of each gap, the at least one heat pipe configured to transfer heat from the multiple vertically disposed windings of the first and second coil stacks.

Additionally or alternatively, the test apparatus further includes at least one cooling fin attached to each of the heat pipes, the at least one cooling fin configured to facilitate heat transfer.

Additionally or alternatively, the stroke of the travel of the testing device is at least 70 mm.

Additionally or alternatively, the suspension system of the test apparatus includes a first side frame and a second side frame configured to support the moving part , each of the first and second coil assemblies being located between the first side frame and the second side frame, the suspension system further including an upper mounting plate for mounting to each of the first and second side frames and the first and second coil assemblies, the suspension system further being mounted to each of the first and second side frames and the first and second coil assemblies.

Additionally or alternatively, the first and second side frames of the test apparatus each have an I-shaped cross section, the first cooling duct is attached to the first side frame such that a space between the top and bottom of the first side of the I-shaped cross section of the first side frame defines an air path, the second cooling duct is attached to the first side frame such that a space between the top and bottom of the second side of the I-shaped cross section of the first side frame defines an air path, the third cooling duct is attached to the second side frame such that a space between the top and bottom of the first side of the I-shaped cross section of the second side frame defines an air path, and the second cooling duct is attached to the second side frame such that a space between the top and bottom of the second side of the I-shaped cross section of the second side frame defines an air path.

In another exemplary embodiment, a linear motor comprises a multi-phase stator assembly including at least one stack having a plurality of cores and a moving part adjacent to the multi-phase stator assembly and configured to move relative to the multi-phase stator assembly when power is supplied to the multi-phase stator assembly; and a suspension system configured to support the moving part and control movement of the moving part relative to the multi-phase stator assembly, the suspension system configured to operate without sliding or rolling contact between the moving part and the suspension system.

Additionally or alternatively, the linear motor is a three-phase linear motor and the multi-phase stator assembly is a three-phase stator assembly.

Additionally or alternatively, the multi-phase stator assembly of the linear motor includes a first coil subassembly and a second coil subassembly, the moving portion being positioned and extending between the first coil subassembly and the second coil subassembly, and the moving portion including a plurality of permanent magnets disposed thereon.

Additionally or alternatively, the first coil subassembly of the linear motor is a laminated magnetic core including multiple poles around which multiple vertically arranged windings are wound to create a first coil stack, and the second coil subassembly is a laminated magnetic core including multiple poles around which multiple vertically arranged windings are wound to create a second coil stack.

Additionally or alternatively, the magnetic core of the first coil assembly of the linear motor includes six poles and six vertically arranged windings, the magnetic core of the second coil assembly includes six poles and six vertically arranged windings, the top and fourth windings of each of the first and second coil stacks are connected to a first phase of the three-phase linear motor, the second and fifth windings of each of the first and second coil stacks are connected to a second phase of the three-phase linear motor, and the third and sixth windings of each of the first and second coil stacks are connected to a third phase of the three-phase linear motor.

Additionally or alternatively, a gap is located between each of the multiple vertically arranged windings of the first and second coil stacks of the linear motor, and the material testing apparatus further comprises at least one cooling duct configured to provide cooling air through the gap located between each of the multiple vertically arranged windings of the first and second coil stacks.

Additionally or alternatively, the stroke of the moving part of the linear motor is at least 70 mm.

Additionally or alternatively, the method includes providing a linear motor having a multi-phase stator assembly, a moving part proximate to the multi-phase stator assembly, and a suspension system; receiving power by the multi-phase stator assembly; moving the moving part back and forth along a movement axis relative to the multi-phase stator assembly after receiving power by the multi-phase stator assembly; and supporting the moving part with the suspension system by controlling movement of the moving part relative to the multi-phase stator assembly such that there is no sliding or rolling contact between the moving part and the suspension system.

In another exemplary embodiment, a test apparatus includes a linear motor including a stator assembly, a moving part mechanically coupleable to a test body configured to move relative to the stator assembly by operation of the linear motor, the moving part including an array of flat magnets configured to generate movement in the moving part in response to a magnetic field generated by the stator assembly, and a suspension system configured to support the moving part and control movement of the moving part relative to the stator assembly, the suspension system configured to operate without sliding or rolling contact between the moving part and the suspension system.

Additionally or alternatively, the moving portion of the testing apparatus includes a magnet frame having a plurality of permanent magnets disposed therein such that the plurality of magnets are exposed from a first side of the moving portion and from a second side of the moving portion opposite the first side.

Additionally or alternatively, the array of the test device includes two rows of flat tile magnets arranged with alternating polarities.

Additionally or alternatively, each flat tile magnet of the first and second arrays of the test device is mounted on the moving part in a distorted manner such that the bottom and top edges of each flat tile magnet are not perpendicular to the side edges of the flat tile magnet.

Additionally or alternatively, each of the two row arrays of the test fixture includes 14 flat tile magnets.

Additionally or alternatively, the stator assembly of the test apparatus includes a first coil subassembly and a second coil subassembly, the moving portion being located and extending between the first coil subassembly and the second coil subassembly, the first coil subassembly including a plurality of poles around which a plurality of vertically arranged windings are wound to generate the first coil stack, and the second coil subassembly including a plurality of poles around which a plurality of vertically arranged windings are wound to generate the second coil stack.

Additionally or alternatively, the array of planar magnets extends a first length along the moving portion of the test apparatus that is longer than the second lengths of each of the first and second coil stacks.

Additionally or alternatively, the moving portion of the test apparatus includes a magnet frame having a first side proximate the first coil assembly and a second side opposite the first side proximate the second coil assembly, the moving portion further including a first bushing shaft, a second bushing shaft, a top end plate, and a bottom end plate, the top end plate and the bottom end plate connecting the first and second air bushing shafts to the magnet frames such that a first space extends parallel to the movement axis between the first bushing shaft and the magnet frame, and a second space extends parallel to the movement axis between the second air bushing shaft and the magnet frame.

Additionally or alternatively, the stroke of the travel of the testing device is at least 70 mm.

Additionally or alternatively, each of the flat magnets of the test device includes a thickness between 10 mm and 22 mm, and each of the flat magnets is a permanent neo magnet.

In another exemplary embodiment, a linear motor includes a stator assembly configured to receive electrical power, a moving part mechanically coupleable to a test body configured to move relative to the stator assembly when the stator assembly receives electrical power, the moving part including an array of planar magnets configured to cause movement in the moving part in response to a magnetic field generated by the stator assembly, and a suspension system configured to support the moving part and control movement of the moving part relative to the stator assembly, the suspension system configured to operate without sliding or rolling contact between the moving part and the suspension system.

Additionally or alternatively, the moving part of the linear motor includes a magnet frame having a plurality of permanent magnets disposed therein such that the plurality of magnets are exposed from a first side of the moving part and from a second side of the moving part opposite the first side.

Additionally or alternatively, the linear motor array includes two rows of flat tile magnets arranged with alternating polarities.

Additionally or alternatively, each flat tile magnet of the first and second arrays of the linear motor is attached to the moving part in a skewed manner such that the bottom and top edges of each flat tile magnet are not perpendicular to the side edges of the flat tile magnet.

Additionally or alternatively, each of the two row arrays of the linear motor includes 14 flat tile magnets.

Additionally or alternatively, the stator assembly of the linear motor includes a first coil subassembly and a second coil subassembly, the moving portion being located and extending between the first coil subassembly and the second coil subassembly, the first coil subassembly including a plurality of poles around which a plurality of vertically arranged windings are wound to generate a first coil stack, and the second coil subassembly including a plurality of poles around which a plurality of vertically arranged windings are wound to generate a second coil stack.

Additionally or alternatively, the array of planar magnets extends a first length along the moving portion of the linear motor that is longer than the second lengths of each of the first and second coil stacks.

Additionally or alternatively, the moving part of the linear motor includes a magnet frame having a first side proximate the first coil assembly and a second side opposite the first side proximate the second coil assembly, the moving part further including a first bushing shaft, a second bushing shaft, a top end plate, and a bottom end plate, the top end plate and the bottom end plate connecting the first and second air bushing shafts to the magnet frames such that a first space extends parallel to the movement axis between the first bushing shaft and the magnet frame, and a second space extends parallel to the movement axis between the second air bushing shaft and the magnet frame.

Additionally or alternatively, the stroke of the moving part of the linear motor is at least 70 mm.

In another exemplary embodiment, a method includes providing a stator assembly, a moving part proximate the stator assembly having an array of flat magnets disposed thereon, and a suspension system; receiving power by the stator assembly; exposing the array of flat magnets to a magnetic field generated by the stator assembly; creating back and forth movement of the moving part relative to the stator assembly by the array of flat magnets; and supporting the moving part with the suspension system by controlling the movement of the moving part relative to the multi-phase stator assembly such that there is no sliding or rolling contact between the moving part and the suspension system.

In another exemplary embodiment, a test apparatus includes a linear motor including a stator assembly and a moving part mechanically coupleable to a test body configured to move relative to the stator assembly by operation of the linear motor, a suspension system configured to support the moving part and control the movement of the moving part relative to the stator assembly, the suspension system configured to operate without sliding or rolling contact between the moving part and the suspension system, and a magnetic damping system configured to absorb kinetic energy of the movement of the moving part when power is disconnected to the linear motor.

Additionally or alternatively, the magnetic damping system of the test apparatus includes a magnet array disposed on a frame of the suspension system parallel to the axis of movement of the moving part , the magnet array configured to absorb kinetic energy of the movement of the moving part when power is disconnected to the linear motor, and the magnet array configured to provide damping during operation of the linear motor to improve control of the movement of the moving part .

Additionally or alternatively, the magnet array of the magnetic damping system of the test apparatus is separate from the magnets used to create the movement of the moving part by the linear motor, and the magnet array is positioned adjacent to a conductive non-magnetic surface of the moving part extending parallel to the axis of movement of the moving part .

Additionally or alternatively, a gap of less than 1 cm exists between the magnet array and the conductive non-magnetic surface of the moving part of the test apparatus.

Additionally or alternatively, the linear motor of the test device is a three-phase linear motor and the magnetic damping system is configured to simultaneously short out power to each of the three phases.

Additionally or alternatively, the stator assembly of the test apparatus includes a first coil subassembly and a second coil subassembly, the first coil subassembly including a plurality of poles around which a plurality of vertically arranged windings are wound to create a first coil stack, and the second coil subassembly including a plurality of poles around which a plurality of vertically arranged windings are wound to create a second coil stack.

Additionally or alternatively, movement of the moving part of the test apparatus relative to the first coil subassembly and the second coil subassembly immediately after power is short-circuited is configured to generate an electromagnetic force that generates a current and a force that resists movement of the moving part .

Additionally or alternatively, the magnetic damping system of the test apparatus includes a first magnet array arranged on a frame of the suspension system parallel to the axis of movement of the moving part adjacent a first side of the moving part , and the magnetic damping system includes a second magnet array arranged on the frame of the suspension system parallel to the axis of movement of the moving part adjacent a second side of the moving part .

Additionally or alternatively, the first and second magnet arrays of the magnetic damping system of the testing apparatus are separate from the magnets used to generate movement of the moving part by the linear motor, the first magnet array is positioned proximate to a first conductive non-magnetic surface of the moving part extending parallel to the movement axis of the moving part , and the second magnet array is positioned proximate to a second conductive non-magnetic surface of the moving part extending parallel to the movement axis of the moving part , and the first and second arrays of magnets are configured to absorb kinetic energy of the movement of the moving part when power is cut to the linear motor.

Additionally or alternatively, each magnet in the magnet array of the test fixture is a flat tile permanent neo magnet.

In another exemplary embodiment, a linear motor includes a stator assembly configured to receive electrical power, a moving part mechanically coupleable to a test body configured to move relative to the stator assembly when the stator assembly receives electrical power, and a suspension system configured to support the moving part and control movement of the moving part relative to the stator assembly, the suspension system configured to operate without sliding or rolling contact between the moving part and the suspension system, and a magnetic damping system configured to absorb kinetic energy of the moving part movement when electrical power is disconnected to the linear motor.

Additionally or alternatively, the magnetic damping system of the linear motor includes a magnet array disposed on a frame of the suspension system parallel to the axis of movement of the moving part , the magnet array being configured to absorb kinetic energy of the movement of the moving part when power is disconnected to the linear motor.

Additionally or alternatively, the magnet array of the magnetic damping system of the linear motor is separate from the magnets used to generate the movement of the moving part by the linear motor, and the magnet array is positioned adjacent to a conductive non-magnetic surface of the moving part extending parallel to the axis of movement of the moving part .

Additionally or alternatively, a gap of less than 1 cm exists between the array of magnets and the conductive non-magnetic surface of the moving part of the linear motor.

Additionally or alternatively, the linear motor is a three-phase linear motor and the magnetic damping system is configured to simultaneously short-circuit power to each of the three phases.

Additionally or alternatively, the stator assembly of the linear motor includes a first coil subassembly and a second coil subassembly, the first coil subassembly including a plurality of poles around which a plurality of vertically arranged windings are wound to create a first coil stack, and the second coil subassembly including a plurality of poles around which a plurality of vertically arranged windings are wound to create a second coil stack.

Additionally or alternatively, movement of the moving part of the linear motor relative to the first coil subassembly and the second coil subassembly immediately after power is shorted is configured to generate an electromagnetic force that generates a current and a force that resists the movement of the moving part .

Additionally or alternatively, the magnetic damping system of the linear motor includes a first magnet array arranged on a frame of the suspension system parallel to the axis of movement of the moving part adjacent a first side of the moving part , and the magnetic damping system includes a second magnet array arranged on the frame of the suspension system parallel to the axis of movement of the moving part adjacent a second side of the moving part .

Additionally or alternatively, the first and second magnet arrays of the magnetic damping system of the linear motor are separate from the magnets used to generate the movement of the moving part by the linear motor, the first magnet array is positioned adjacent to a first conductive non-magnetic surface of the moving part extending parallel to the movement axis of the moving part and the second magnet array is positioned adjacent to a second conductive non-magnetic surface of the moving part extending parallel to the movement axis of the moving part, and the first and second magnet arrays are configured to absorb kinetic energy of the movement of the moving part when power is cut to the linear motor.

In another exemplary embodiment, a method includes providing a stator assembly, a moving part proximate to the stator assembly, a suspension system, and a magnetic damping system; receiving power by the stator assembly; moving the moving part back and forth relative to the stator assembly after receiving power by the stator assembly; supporting the moving part with the suspension system by controlling the movement of the moving part relative to the stator assembly such that there is no sliding contact or rolling between the moving part and the suspension system; disconnecting power to the stator assembly; and absorbing kinetic energy of the movement of the moving part by the magnetic damping system when power is disconnected to the linear motor.

The above and further advantages of the present invention may be better understood by reference to the following description in conjunction with the accompanying drawings, in which like reference numerals indicate like elements and features in the various drawings. For purposes of clarity, not every element may be labeled in every figure. Also, the drawings are not necessarily to scale, emphasis instead generally being placed on illustrating the principles of the invention.

FIG. 1 illustrates a perspective view of a linear motor, according to one embodiment. 2 illustrates a cutaway view of the linear motor of FIG. 1 taken at arrows AA, according to one embodiment. FIG. 2 illustrates a perspective view of the linear motor of FIG. 1 with cooling ducts shown, according to one embodiment. FIG. 4 illustrates a perspective view of a first side frame of the linear motor of FIGS. 1 and 3 , revealing the top surface, according to one embodiment. FIG. 4 illustrates a perspective view of a second side frame of the linear motor of FIGS. 1 and 3 , revealing the underside, according to one embodiment. FIG. 6 illustrates a perspective view of a frame subassembly including the first and second side frames of FIGS. 4 and 5 connected between upper and lower plates oriented to expose the upper side, according to one embodiment. FIG. 7 illustrates a perspective view of the frame subassembly of FIG. 6 oriented to reveal an underside, according to one embodiment. FIG. 5 illustrates a perspective cutaway view of the first side frame of FIG. 4 showing two air bushings disposed within the vertical opening, according to one embodiment. FIG. 4 shows a perspective view of the moving part of the linear motor of FIGS. 1 and 3 according to one embodiment. FIG. 10 shows a perspective view of a magnet frame of the moving part of FIG. 9 according to one embodiment. FIG. 11 illustrates an enlarged perspective view of a portion of the magnet array of the magnet frame of FIG. 10 according to one embodiment. FIG. 4 illustrates a perspective view of a coil subassembly of the linear motor of FIGS. 1 and 3 according to one embodiment. FIG. 13 illustrates a side view of a portion of the coil subassembly of FIG. 12 according to one embodiment. FIG. 13 illustrates a perspective view of a coil bobbin with integrated cooling fins of the coil assembly of FIG. 12 according to one embodiment. FIG. 13 illustrates a perspective view of the coil subassembly of FIG. 12 with heat pipes and additional cooling fins according to one embodiment. FIG. 4 illustrates an electrical schematic of a three-phase motor of the linear motor of FIGS. 1 and 3 , according to one embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention provides numerous advances within the field of testing systems, and more specifically, frictionless material handling systems. As used herein, a frictionless material testing system is a material testing system configured to operate without contact (sliding, rolling, etc.) between A) a moving part (e.g., a moving section ) that can be coupled to a material under test, and B) a suspension system that supports the moving part. Material testing systems, including the frictionless material testing systems described herein, may be configured to exert a back and forth linear force and/or motion on a material, device, apparatus, or other object under test under test. Frictionless material testing systems have been found to have superior reliability, sensitivity, and cleanliness compared to systems that operate with sliding or rolling contact.

Prior art frictionless material testing systems have traditionally been limited in stroke range due to the fact that the moving parts coupled to the test specimen and the suspension system require the mounting of a magnet carrier between the flexible suspension components, as known concepts for creating controlled movement between the suspension system require the mounting of a magnet carrier between the flexible suspension components. When one or more magnets held by the magnet carrier are exposed to a magnetic field created by a single-phase linear motor, the flexible suspension components bend. While this configuration is frictionless (i.e., the bending flexible suspension components do not impart any contact-based friction), the range of movement is limited by the material properties of the flexible suspension components.

The present invention provides a frictionless material testing system with an increased stroke range. The system described herein does not require any flexible suspension components to be directly connected between the moving part and the suspension system. Rather, embodiments of the present invention include a moving part that moves relative to a suspension system that is not directly connected to any flexible suspension support.

An embodiment of the present invention includes a material testing system that includes a multi-phase linear motor having a stack of multiple cores configured to provide a desired longer stroke distance. For example, the present invention includes a material testing system that includes a three-phase linear motor, where each phase of the motor controls one or more windings or coils in the stack of coils. The multiple phases can provide control of the moving parts over a larger vertical stroke distance than is achievable with a single-phase motor.

The embodiments described herein include a frictionless material testing system having a moving part supported by an air bushing suspension system for controlling the movement of the moving part over a larger stroke distance without sliding friction. When the moving part is powered by a linear motor, the air bushing suspension system is configured to prevent bending or twisting of the moving part caused by magnetic attraction and to maintain a distance between the moving part and one or more stator assemblies.

An embodiment of the present invention further includes a frictionless material testing system having a magnetic transfer part for integration with a linear motor having a stator assembly including one or more stacks of coils for moving the magnetic transfer part . An embodiment of the present invention includes using an array of diagonally arranged flat tile magnets. The magnetic transfer part described herein further includes a magnet array extending through the magnet frame such that the magnets are exposed on two opposing sides or surfaces of the transfer part , each of the two opposing sides or surfaces being proximate to a respective stator coil stack.

Further described herein is a frictionless material testing system having a stopping or braking system that includes a magnetic damping system for providing damping when the frictionless material testing system is stopped. Embodiments include using electromagnetic forces generated by the movement of a moving part of the system to generate a force that opposes the movement and slows the moving part . In embodiments that use a multi-phase linear motor, embodiments of the frictionless material testing system include a system configured to disconnect or short power to each phase simultaneously.

Further describing a cooling approach for cooling the linear motor of the frictionless material testing system. The cooling system described herein utilizes recycled air supplied to the air bushings of the suspension system to cool components of the linear motor, such as the windings or coils. Other novel approaches to embodiments of the cooling system of the present invention include utilizing a coil bobbin with fins to optimize heat removal, and a heat pipe extending from a gap located between the windings of the coil stack, and additional cooling fins attached thereto.

The present teachings will now be described in more detail with reference to exemplary embodiments thereof, as illustrated in the accompanying drawings. While the present teachings have been described in conjunction with various embodiments and examples, it is not intended that the present teachings be limited to such embodiments. On the contrary, the present teachings encompass various alternatives, modifications, and equivalents, as will be appreciated by those of skill in the art. Those having skill in the art with access to the teachings herein will recognize additional implementations, modifications, and embodiments, as well as other fields of use, that are within the scope of the disclosure described herein.

Any reference in the specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment of the teachings. References to particular embodiments within this specification do not necessarily all refer to the same embodiment.

Referring now to the drawings, FIG. 1 shows a perspective view of a materials testing apparatus 10 including a linear motor 100 according to one embodiment. The linear motor 100 is shown to include a moving portion 200, a suspension system 300, and a stator assembly 400. The moving portion 200 includes an output shaft 210 extending from a bottom end that can be mechanically coupled to a test specimen (not shown). The moving portion 200, and thereby the output shaft 210, are configured to be moved back and forth by the operation of the linear motor 100 along a translation axis 500, as described herein. The stroke length of the moving portion 200 may be greater than 70 mm in one embodiment. In other embodiments, the stroke length of the moving portion 200 may be greater than 80 mm, 90 mm, or 100 mm. The materials testing apparatus 10 may be configured with any necessary stroke length to adequately perform a test on a given specimen or material.

The suspension system 300 is configured to support the moving part 200 and control the movement of the moving part 200 relative to the stator assembly 400 without any contact, such as sliding or rolling contact, between the moving part 200 and the suspension system 300. By moving along the movement axis 500, the moving part 200 can be configured to apply a force to a test specimen, inducing either a motion or a mechanical stress (or both) along the movement axis 500.

The linear motor 100, traveler 200, suspension system 300, and stator assembly 400 are shown in more detail in subsequent figures. The mechanical attachment between the output shaft 210 and the test specimen may be conventional. For example, the configuration of the test specimen may depend on the particular material test to be performed. The test specimen may be considered to be any material, component, jig, fixture, device, etc.

The moving part 200 may be a magnetic device having a magnet array 212 positioned or otherwise arranged within a magnet frame 214. Although not shown, the magnet array 212 extends through the magnet frame 214 on the opposite side of the moving part 200. Although only one side of the moving part 200 is shown, the moving part 200 may be geometrically symmetrical or substantially symmetrical about a first plane of symmetry extending parallel to both the movement axis 500 and a horizontal axis 510 perpendicular to the movement axis, as shown in the figure. The moving part 200 may also be magnetically and geometrically symmetrical or substantially symmetrical about a second plane of symmetry extending parallel to the movement axis 500 and a second horizontal axis 520 perpendicular to the movement axis and further perpendicular to the first movement axis.

The moving part 200 is held in place by a suspension system 300 including a first side frame 310 and a second side frame 312. The first and second side frames 310, 312 are configured to support the moving part 200. The suspension system 300 may be a structure (e.g., the first and second side frames 310, 312) including at least one opening (e.g., the first and second moving part openings 395, 397 shown in Figs. 6 and 7) for receiving the moving part 200 therein, although other embodiments are contemplated. The coil stack in the stator assembly 400 is located between the first and second side frames 310, 312. The suspension system 300 further includes a top mounting plate 314 and a bottom mounting plate 316 for attaching, connecting, or otherwise mounting the first and second side frames 310, 312 and the stator assembly 400.

In the illustrated embodiment, the linear motor 100 is a three-phase linear motor. Figure 2 shows a cutaway view of the linear motor 100 of Figure 1 taken at arrows A-A according to one embodiment. The linear motor 100 includes a first coil subassembly 414 having a first coil stack 410 and a second coil subassembly 416 having a second coil stack 412 housed within a stator assembly 400 adjacent two opposing sides of the magnet array 212 exposed on either side of the magnet frame 214 of the moving part 200. When powered, the coil stacks of the stator assembly 400 provide the movement of the magnetic moving part 200.

The first coil subassembly 414 includes a first laminated magnetic core 422 having six separate poles 418a, 418b, 418c, 418d, 418e, 418f wound with six separate windings 420a, 420b, 420c, 420d, 420e, 420f, respectively, which generate the first coil stack 410. Similarly, the second coil subassembly 416 includes a second laminated magnetic core 422 having six separate poles 424a, 424b, 424c, 424d, 424e, 424f wound with six separate windings 426a, 426b, 426c, 426d, 426e, 426f, respectively, which generate the second coil stack 412. As shown, the first phase A is connected from the top to the top winding 420a, 426a of the first and second coil stacks 410, 412, respectively, along with the fourth winding 420d, 426d. The second phase B is connected from the top to the second winding from the top 420b, 426b of the first and second coil stacks 410, 412, respectively, along with the fifth winding 420e, 426e. The third phase C is connected from the top to the third winding from the top 420c, 426c of the first and second coil stacks 410, 412, respectively, along with the sixth winding 420f, 426f.

As shown, each of the magnets in the magnet array 212 includes an opposite or opposite polarity relative to the magnets directly adjacent to it. Specifically, the magnet array 212 includes 14 rows of two magnets each. Other embodiments may include more or less than 14 rows of two magnets each. For example, a shorter stroke version of the linear motor 100 may include 13, 12, 11, 10 or fewer magnet pairs. A longer stroke version of the linear motor may include 15, 16, 17, 18, 19, 20 or more magnet pairs. This three-phase configuration generates a magnetic field that interacts with the magnet array 212 of the moving part 200 to move the moving part 200 up and down (i.e., back and forth) along the moving axis 500. The magnet array 212 may be positioned proximate to each of the first and second coil stacks 410, 412 within a predetermined gap tolerance. The gap span may be maintained to tight tolerances to prevent the magnet array 212 from being attracted more to one or the other of the first and second coil stacks 410, 412 during operation as much as possible. While it may be impossible to create perfectly equal gaps between each side of the magnet array 212 and the coil stacks 410, 412, the lateral stiffness of the suspension system 300 may be configured to support the lateral forces created by a slightly uneven gap. The lateral stiffness of the suspension system 300, including the air bushings (described in more detail below), may be high enough to counteract any lateral forces caused by an uneven gap.

Although the illustrated embodiment includes a three-phase linear motor with a three-phase stator assembly 400, the principles described herein relating to the moving part 200, suspension system 300, and stator assembly 400 may be incorporated into a single-phase linear motor, or any other multi-phase linear motor. Although it has been discovered that a three-phase system is capable of achieving a higher stroke length than a single-phase system in applications where stroke length is not critical, a single-phase linear motor may also be used without departing from various embodiments of the present invention.

3 shows a perspective view of the linear motor 100 of FIG. 1, with cooling ducts 318, 320, 322 shown according to one embodiment. The cooling ducts 318, 320, 322 may be removably attachable features to each of the first and second side frames 310, 312 of the suspension system 300. As shown, the first cooling duct 318 is attached to the front side of the first side frame 310, and the second cooling duct 320 is attached to the back side of the first side frame 310. Similarly, the third cooling duct 322 is shown attached to the front side of the second side frame 312. Although hidden, a fourth cooling duct may be attached to the back side of the second side frame 312. Each of the cooling ducts 318, 320, 322 may provide a passage for air to move through the interior. Fans 324, 326, 328 are shown mounted in each cooling duct 318, 320, 322, respectively, to facilitate air circulation, recirculation, and/or blowing through the cooling ducts 318, 320, 322.

Referring now to Figures 4 and 5, Figure 4 illustrates a perspective view of the first side frame 310 of the linear motor 100 of Figures 1 and 3 with the upper surface 330 exposed, according to one embodiment. Figure 5 illustrates a perspective view of the second side frame 310 of the linear motor 100 of Figures 1 and 3 with the lower surface 332 exposed, according to one embodiment. The first and second side frames 310, 312 may be symmetrical components having the same dimensions and characteristics. In other embodiments, the first and second side frames 310, 312 may each include one or more unique features, dimensions, etc. (not shown).

The first and second side frames 310, 312 of the suspension system 300 may be dimensioned to support air flow from the ducts 318, 320, 322 into the gaps located between the windings 420a, 420b, 420c, 420d, 420e, 420f, 426a, 426b, 426c, 426d, 426e, 426f of the stator assembly 400 and/or over the magnets of the magnet array 212. To achieve this, the first and second side frames 310, 312 may each include an I-shaped cross section. Thus, each of the first and second side frames 310, 312 includes an upper portion 340, 342, respectively, an intermediate portion 344, 346, respectively, and a lower portion 348, 350, respectively. Referring again to FIG. 3, the cooling ducts 318, 320, 322 are attached between the top and bottom of the I-shaped cross section such that the first and second side frames 310, 312 define an air passage from the cooling ducts 318, 320, 322 to the stator assembly 400 and/or magnet array 212. In other embodiments, the shape of the first and second side frames 310, 312 may be more solid than in the embodiment shown and may include openings, slots, ports, etc. to facilitate air flow.

4 and 5, the first side frame 310 includes a first opening 334 having an air bushing 336a disposed therein, and the second side frame 312 includes a second opening 338 having another air bushing 336b disposed therein. The first and second openings 334, 338 are cylindrical openings having circular cross sections configured to receive cylindrical air bushings 336a, 336b (hereinafter generally referred to as air bushings 336), respectively. However, in other embodiments, openings of other shapes are contemplated. For example, triangular or rectangular openings may be used in the first and second side frames 310, 312 having arrays of opposing flat bearings rather than utilizing cylindrical air bushings 336 without departing from the scope of the various inventive concepts described herein.

Each of the first and second side frames 310, 312 further includes a magnetic damping system configured to absorb kinetic energy from the movement of the moving part 200 when power to the linear motor 100 is cut off. Specifically, the magnetic damping system is shown as two arrays of magnets 380a, 380b, one disposed on each of the first and second side frames 310, 312 parallel to the axis of movement 500 of the moving part 200. In addition to absorbing kinetic energy when power is cut off, the magnetic damping system may be configured to reduce instabilities and make the linear motor 100 more stable. For example, during normal operation, the magnetic damping system may be tuned by adjusting the gap or by using a different number or type of magnets to provide an optimal amount of damping to improve system control.

While FIG. 4 clearly shows a first array of magnets 380a disposed on the first side frame 310, the second side frame 312 includes a second array of magnets 380b (more clearly shown in FIG. 6). Each magnet in each of the arrays of magnets 380a, 380b is shown as a flat tile permanent neo-magnet. These arrays of magnets 380a, 380b are separate from the magnet array 212 utilized by the moving part 200 to cause the linear motor 100 to move the moving part 200. Each of the arrays of magnets 380a, 380b may be positioned adjacent to a conductive non-magnetic surface of the moving part 200 that extends parallel to the axis of movement 500 of the moving part 200 when the linear motor 100 is assembled and in operation. A small gap (e.g., less than 1 cm, less than 5 cm, or less than 25 cm) exists between each of the arrays of magnets 380a, 380b and the conductive non-magnetic surface of the moving part 200 to which they are located in close proximity (as shown more clearly in FIG. 10 and described below). The first and second arrays of magnets 380a, 380b may be configured to utilize eddy currents induced by the motion of the conductive non-magnetic surface of the moving part 200 to resist movement, thereby creating a damping effect on the moving part during a stopped state. The number of magnets shown in each of the first and second arrays of magnets 380a, 380b is 12, although more or fewer magnets may be provided. Each of the arrays of magnets 380a, 380b includes a single row of magnets vertically disposed on the magnet holding surfaces 382a, 382b of the first and second side frames 310a, 310b, respectively. The magnet retention surfaces 382a, 382b may be vertically sized protrusions extending from a surface of each of the first and second side frames 310a, 310b that is adjacent the moving part 200 when the linear motor 100 is assembled and in operation.

The upper and lower surfaces of the first and second side frames 310, 312 may each include one or more alignment pins 352, 354. For example, the upper surface 330 of the first side frame 310 includes a first alignment pin 352 to facilitate attachment between the first side frame 310 and the upper plate 356. The lower surface 332 of the second side frame 312 is shown to include a second alignment pin 354 to facilitate attachment between the second side frame 312 and the lower plate 358. Although only the upper surface of the first side frame 310 and the lower surface 332 of the second side frame 312 are shown, it should be understood that alignment pins may also be included on the lower surface of the first side frame 310 and the upper surface of the second side frame 312. The upper and lower surfaces of each of the first and second side frames 310, 312 may further include, for example, threaded openings 360 to receive attachment mechanisms such as threaded screws, bolts, etc., for attaching the first and second side frames 310, 312 to the upper and lower plates 356, 358.

The first and second side frames 310, 312 each include two air supply openings 384 for each air bushing 336 configured to be disposed within the first opening 334 and the second opening 338, respectively. The air supply openings 384 may be configured to supply forced air to the air bushing 336 from an air source (not shown). The air supply openings 384 may be configured to directly receive air or may be configured to receive a tube, pipe, or other device configured to pass air therethrough. The first and second side frames 310, 312 further include three pressure relief openings 386 for each bushing configured to be disposed within the first opening 334 and the second opening 338. The air supply openings 384 and the pressure relief openings 386 are shown in FIG. 7 and described in more detail below.

6 shows a perspective view of a frame subassembly 370 including the first and second side frames 310, 312 of FIGS. 4 and 5 connected between upper and lower plates 356, 358 oriented to expose the upper side 362, according to one embodiment. FIG. 7 shows a perspective view of a frame subassembly 370 including the first and second side frames 310, 312 of FIGS. 4 and 5 connected between upper and lower plates 356, 358 oriented to expose the lower side 364, according to one embodiment. The upper and lower plates 356, 358 are configured to attach the first and second side frames 310, 312 together and also provide mounting locations for mounting the first and second coil stacks 410, 412 of the stator assembly 300. Thus, the upper and lower plates 356, 358 may include various openings, e.g., threaded, to receive mounting screws, bolts, for assembling the frame subassembly 370, or other mechanisms for further attaching the frame subassembly 370 to other components (not shown) of the materials testing system 10.

The upper and lower plates 356, 358 may each include multiple x,y location openings 368a, 368b, 368c and clocking slots 366a, 366b, 366c to facilitate assembly. The x,y location openings 368a, 368b, 368c may be circular openings to receive circular pins and prevent movement between the plates 356, 358 and the side frames 310, 312 through which the pins extend. The clocking slots 336a, 336b, 336c may be elongated along the direction of movement and provide some movement between the plates 356, 358 and the side frames 310, 312 through which the pins extend.

To assemble the linear motor 100 and its frame subassembly 370, after the travel portion 200 is placed within the frame subassembly 370, pins may be inserted into the x,y location openings 368b, 368c and the clocking slots 336b, 336c, respectively, of the lower plate 358. The pins may then be inserted into the x,y location openings 368a and the clocking slots 366a of the upper plate 356. Once the pins are placed through the clocking slots 336a, 336b, 336c and the x,y location openings 368a, 368b, 368c, the method of assembling the linear motor 100 includes exciting the air bushings 336 in the first and second vertical openings 334, 338. This air pressure, in conjunction with the limited movement provided by the clocking slots 366a, 366b, 366c, may align the system after which the upper and lower plates 356, 356 may be fully tightened with bolts, screws, or the like.

Each of the upper and lower plates 356, 358 may include the same dimensions and features. For example, each of the upper and lower plates 356, 358 may include two transfer shaft openings 394a, 394b, 394c, 394d configured to receive a transfer shaft therein. When assembled, the first opening 334 of the first side frame 310 is aligned with the transfer shaft openings 394a, 394c, and the second opening 338 of the second side frame 312 is aligned with the transfer shaft openings 394b, 394d, providing left and right collective vertical openings each extending through each of the upper plate 356, the respective first and second side frames 310, 312, and the lower plate 358. Each of the collective vertical openings extends along an axis parallel to the axis of movement 500.

A first mover opening 395 extends between the openings 394a, 394b in the top plate 356, and a corresponding second mover opening 397 extends between the openings 394c, 394d in the bottom plate 358. The mover openings 395, 397 may be configured to receive the mover therein and provide free movement of the mover . An upper bump stop 390a is shown extending from the top plate 356, and a lower bump stop 390b extends from the bottom plate 358. The bump stops 390a, 390b may provide a physical boundary for the movement of the mover 200. The bump stops 390a, 390b may be made of a soft elastomeric material, such as an FKM elastomer, to slow deceleration.

The top plate 356 is shown to include first and second stack mounting surfaces 392a, 392b. Similarly, the bottom plate 358 is shown to include third and fourth stack mounting surfaces 392c, 392d. The stack mounting surfaces 392a, 392b provide a surface upon which the first coil stack 410 is mounted. Similarly, the stack mounting surfaces 392c, 392d provide a surface upon which the second coil stack 412 is mounted. Accordingly, the stack mounting surfaces 392a, 392b, 392c, 392d each include a number of openings that may be configured with threads to receive screws, bolts, or the like. The dimensions that the stack mounting surfaces 392a, 392b, 392c, 392d extend into the top and bottom plates 356, 358 may be precisely machined to provide a desired gap distance between the moving transfer portion 200 and the first and second coil stacks 410, 412.

8 shows a perspective cutaway view of the first side frame 310 showing two air bushings 336a, 336c disposed within the vertical opening 334 of the first side frame 310 according to one embodiment. Although only the first side frame 310 is shown cut away in FIG. 8 to reveal the two air bushings 336a, 336c within the vertical opening 334, the second side frame 312 may similarly further include two air bushings 336. Thus, the following description of the air bushings 336a, 336c is applicable to the two air bushings 336 located within the second side frame 312.

As shown, the first air bushing 336a of the first side frame 310 is located adjacent to a first upper end of the opening 334, and the second air bushing 336b is located adjacent to a second lower end of the opening 334. The air bushings 336a, 336b may each be installed within the opening 334 in a manner adapted to allow some movement between the air bushings 336a, 336b and the frame subassembly 370. This fitting relationship may be provided by inserting the air bushings 336a, 336b into the opening 334 with an interference fit or press fit. Additionally, the air bushings 336a, 336b may each be made of a corresponding elastomeric material and are shown to include a number of O-rings 372 that may provide some fit between the air bushings 336a, 336b and the opening 334 (and thereby the frame subassembly 370). Each of the air bushings 336a, 336b may be installed by manually inserting it into the opening 334 and may be manually removed, for example, for maintenance.

The air bushings 336a, 336b each have a hollow cylindrical shape. The air bushings 336a, 336b each include an outer body 374 and an inner body 378 made of different materials. The inner body is a porous body permeable to air, while the outer body 374 is impermeable to air except through the air receiving port openings 376. This allows air to be received into each of the air bushings 336a, 336b through the respective air receiving port openings 376. This air is then transported through the porous inner body 378. Since the outer body 374 is impermeable to air and prevents the air received by the air receiving port openings 376 from leaking out through the outer body 374, the received air is forced to escape only through the porous inner body 378, thereby generating air pressure between the porous inner body 378 and the shaft of the moving part received therein. The porous inner body 378 includes many (thousands, millions, etc.) sub-micron pores that create a permeability to air within the material. When the air bushings 336a, 336b receive air through the air receiving port opening 376, the air bushings 336a, 336b may be configured to provide full 360 degree non-contact movement for the shaft of a moving part received therein, as the air escapes the body of the air bushings 336a, 336b through the inner body 378.

As shown in the cutaway, the air supply openings 384 of the first side frame 310 extend through the body of the frame and are directly aligned with the respective receiving port openings 376. Pressure relief openings 386 also extend through the body of the frame and are aligned with the spaces between each of the four O-rings 372 on the bushings. The pressure relief openings 386 in the body of the first side frame 310 can facilitate installation of the air bushings 336a, 336b and prevent the build-up of air pressure between the outer bodies 374 of the air bushings 336a, 336b and the inner walls of the vertical openings 334 of the first side frame 310. Additional openings may be provided from within the vertical opening 334 of the first side frame 310 to recycle air introduced into the bushings 336a, 336b and returned to the system through the respective receiving port options 376 for the purpose of cooling at least one of the windings 420a, 420b, 420c, 420d, 420e, 420f, 426a, 426b, 426c, 426d, 426e, 426f or the magnet array 212 of the moving part 200.

Although the test fixture 10 and linear motor 100 are shown to include four air bushings 336 (two on each of the first and second side frames 310, 312), more or fewer air bushings may be included if necessary to accommodate any crushing forces caused by the magnetic attraction between the mover 200 and the coil stacks 410, 412. For example, some embodiments may require only two air bushings. Other embodiments may require six air bushings (three on each of the vertical openings 334, 338). In another contemplated embodiment, one or more additional air bushings may be configured to surround the test specimen output shaft 210 extending from the mover 200 to provide additional suspension support for the system.

FIG. 9 shows a perspective view of the moving part 200 of the linear motor 100 of FIGS. 1 and 3 according to one embodiment. The moving part 200 includes a magnet frame 214 with a magnet array 212 extending between a top end plate 220 and a bottom end plate 222 in the direction of the moving axis 500. The top end plate 220 and the bottom end plate 222 are configured to connect, attach or otherwise assemble the magnet frame 214 and the magnet array 212 to a first side air bushing shaft 230 and a second side air bushing shaft 232. The first and second side air bushing shafts 230, 232 also extend in the moving axis 500. The first and second side air bushing shafts 230, 232 are shown as cylindrical shafts. The first and second side air bushing shafts 230, 232 have tight dimensional tolerances with respect to the inner dimensions of the air bushings 336 in the first and second openings.

The air bushing 336 is configured to provide frictionless movement between the moving part 200 and the frame subassembly 370 of the suspension system 300. The air bushing 336 operates without sliding or rolling friction between the inner surface of the air bushing 336 and the air bushing shafts 230, 232 of the moving part 200. When air is forced through the inner body 378 of the air bushing 336, the air bushing shafts 230, 232 of the moving part 200 are forced through the air to a midpoint between the inner surfaces of the inner body 378. In one embodiment, the air bushings 230, 232 may have a radius that is 3-5 microns smaller than the inner radius of the inner surface of the air bushing 336 to provide a space between the air bushing shafts 230, 232 and the inner surface of the inner body 378 of the air bushing 336 when the air bushing 336 receives the air flow and the system is operating. In one embodiment, the air bushing shafts 230, 232 have a radius that is 4 microns smaller (8 microns smaller diameter) than the inner surface of the air bushing 336. Other dimensions are contemplated to provide a frictionless and/or contactless movement system between the air bushing shafts 230, 232 and the air bushing 336.

The top and bottom end plates 220, 222 are shown to have a width that is greater than the width of the magnet frame 214. This greater width provides a surface for engagement with the bump stops 390a, 390b. Additionally, the top and bottom end plates 220, 222 include connection openings 234 that receive bolts, screws, or other attachment mechanisms for connection to the magnet frame 214. Various other connection openings may be provided to receive other bolts, screws, etc. to attach the top and bottom end plates 220, 222 to the air bushing shafts 230, 232. The top and bottom end plates 220, 222 are shown connecting the first and second air bushing shafts 230, 232 to the magnet frame 214 such that a first space extends parallel to the axis of movement 500 between the first air bushing shaft 230 and the magnet frame 214, and similarly a second space extends parallel to the axis of movement between the second air bushing shaft 232 and the magnet frame 214. These spaces may be larger than the thickness of the air bushing 336 and the body of the first and second side frames 310, 312 surrounding the vertical openings 334, 338. Thus, these vertical spaces between the air bushing shafts 230, 323 and the magnet frame 214 allow the moving part 200 to remain connected to the suspension system 300 while allowing vertical movement of the moving part 200 relative to the suspension system 300.

FIG. 10 illustrates the magnet frame 214 of the traveler 200 of FIG. 9 prior to assembly with the first and second air bushing shafts 230, 232 and the top and bottom end plates 220, 222, according to one embodiment. The magnet frame 214 includes a body extending between an L-shaped side 236 and an L-shaped right side 238. The L-shaped left and right sides 236, 238 extend across the vertical length of the magnet frame 214. The magnet frame 214 is open in the center configured to receive the magnet array 212. Each magnet of the magnet array 212 may be attached to the magnet frame 214 by epoxy around the edges of the magnet array 212 and around the edges of each individual magnet to secure the magnets together. The epoxy may be a temperature resistant epoxy that does not degrade at the high temperatures to which the magnets rise during operation. In other embodiments, the magnets may be attached to the magnet frame 214 via mechanical means, such as via slots in a tile that are integrated with protrusions or slots in the magnet frame 214. Another alternative or additional approach may include utilizing set screws to tighten, compress, or otherwise clamp the magnet by the magnet frame 214 along the edges of the magnet.

Also shown in this figure is an array of magnets 380a mounted on one of the side frames 310, 312, with the side frame removed to show the close dimensional relationship between the array of magnets 380a and the magnet frame 214. The gap between the array magnets 380a and the magnet frame 214 may be optimized to provide a desired damping force when the system is shut off. For example, gaps of 3 mm, 25 mm, 2 mm, 15 mm are contemplated. Any gap that achieves the desired amount of damping through interaction with eddy currents is contemplated.

11 illustrates a portion of the magnet array 212 of the magnet frame of FIG. 10, according to one embodiment. A view of several individual magnets 212a, 212b, 212c, 212d, 212e, 212f, 212g is shown enlarged to show the distortion and size of each of the magnets in the magnet array 212. Each of the magnets 212a, 212b, 212c, 212d, 212e, 212f, 212g in the magnet array 212 (both those shown in FIG. 11 and those extending below the view) may be permanent neo-magnets, such as NdFeB magnets. Each of the magnets 212a, 212b, 212c, 212d, 212e, 212f, 212g in the magnet array 212 is shown distorted at a slight angle, such as a single angle. Thus, magnets 212a, 212b, 212c, 212d, 212e, 212f, 212g may have a parallelogram shape such that the bottom and top edges of each of the flat tile magnets are not perpendicular to the side edges of the flat tile magnets. As shown, the top left edge of each of magnets 212a, 212c, 212e is higher than the top right edge. Similarly, the top right edge of each of magnets 212b, 212d, 212f, 212g is higher than the top left edge. In other words, the magnets are smaller as they approach the center of magnet array 212 than the edges of magnet array 212. This distortion may be reversed so that the magnets are larger as they approach the center of magnet array 212 than the edges of magnet array 212. The distortion may be any suitable amount, such as single degree, two degrees, or three degrees, and may be optimized to reduce cogging forces during interaction with the magnetic field generated by the stator assembly 400.

In an exemplary embodiment, the width of each magnet may be 50-100 mm and the height may be 10-50 mm. The thickness of each magnet may be 10-22 mm. In one exemplary embodiment, the magnets may have a width of 70 mm, a height of 28 mm, and a thickness of 18 mm. These dimensions may be modified depending on the force output required by the magnet array 212.

12 shows a perspective view of the first coil subassembly 414 of the linear motor 100 of FIGS. 1 and 3 according to one embodiment. Although not shown, the second coil subassembly 418 may share the same features and dimensions as the first coil subassembly 414. The coil subassembly 414 is shown to include a first laminated magnetic core 422 having six separate poles 418a, 418b, 418c, 418d, 418e, 418f (generally 418) around which six separate windings 420a, 420b, 420c, 420d, 420e, 420f (generally 420) are wound respectively to create the first coil stack 410. The laminated magnetic core 422 may include many laminations held together by stack press bars on each side. The laminated magnet core 422 may include, for example, 200 laminations (metal sheets) of M19 magnetic steel. The laminations may include fins 428 that may increase the surface area of the laminated magnet core 422 to facilitate cooling. In an exemplary embodiment, the pole spacing between the six separate poles 418a, 418b, 418c, 418d, 418e, 418f may be 20-60 mm. In one embodiment, the pole spacing may be 38 mm. In some embodiments, the pole spacing may be equal between each of the poles 418a, 418b, 418c, 418d, 418e, 418f. In other embodiments, different pole spacing may be advantageous to optimize heat distribution, magnetic field output, etc. In an exemplary embodiment, the thickness of the poles 418a, 418b, 418c, 418d, 418e, 418f may be 10-20 mm. In one embodiment, the pole thickness may be 15.8 mm. The six separate windings 420a, 420b, 420c, 420d, 420e, 420f may be made of, for example, 16 AWG round wire and may include 168 turns. The windings 420a, 420b, 420c, 420d, 420e, 420f may each include six layers with 28 turns per layer. A coil bobbin 440a, 440b, 440c, 440d, 440e, 440f (generally, coil bobbin 440) may further be included with each of the poles 418a, 418b, 418c, 418d, 418e, 418f. Coil bobbins 440a, 440b, 440c, 440d, 440e, and 440f are described below and shown in FIG. 14.

Figure 13 shows a side view of a portion of the coil subassembly 414 of Figure 12, according to one embodiment. After being wound on the poles 418a, 418b, 418c, 418d, 418e, 418f, there may be gaps 430 between the windings 420a, 420b, 420c, 420d, 420e, 420f. The gaps 430 may allow cooling airflow to travel therethrough. The gaps 430 may each have a thickness of several mm. For example, a gap thickness of 4.5 is contemplated between each of the windings 420a, 420b, 420c, 420d, 420e, 420f. The gap thickness may be, for example, 3-10 mm. In other embodiments, the gap thickness may be filled with a potting material as described below and shown in Figure 15.

14 illustrates a perspective view of one of the coil bobbins 440 having integral cooling fins 448a, 448b, 448c, 448d, 448e, 448f according to one embodiment. The coil bobbin 440 includes a body 442 extending from a base 444. The body 442 includes a generally rectangular cross-section that surrounds and defines an opening 446 sized to surround and receive one of the poles 418. The coil bobbin 440 further includes a number of fins 448a, 448b, 448c, 448d, 448e, 448f extending from the body 442. Winding gaps 450a, 450b may be located between the fins 448a, 448b, 448c, 448d, 448e, 448f. The winding gaps allow the wire of the winding 420 to be wound between the sections of the coil bobbin 440. The fins 448a, 448b, 448c, 448d, 448e, 448f of the coil bobbin 440 may be of sufficient height to extend through the winding 420 into the forced convection area between the coils. This allows the coil bobbin 440 to help increase the conduction of heat from the winding 420. The fins 448a, 448b, 448c, 448d, 448e, 448f can further increase the surface area available for forced convection.

15 shows a perspective view of the coil subassembly 414 of FIG. 12 with a heat pipe 475 and additional cooling fins 470 attached thereto, according to one embodiment. This embodiment may be applied in addition to or as an alternative to the coil bobbin 440. In this embodiment, potting material 460a, 460b, 460c, 460d, 460e may be included within each of the gaps between the windings 420a, 420b, 420c, 420d, 420e, 420f. Four heat pipes 475 are shown extending from the potting material within each of the gaps. For example, four heat pipes 475a extend from the left side between the top gaps of the windings, four heat pipes 475b extend from the left side between the second gaps, four heat pipes 475c extend from the left side between the third gaps, four heat pipes 475d extend from the left side between the fourth gaps, and four heat pipes 475e extend from the left side between the fifth gaps. Similarly, four heat pipes 475f extend from the right side between the top gaps of the windings, four heat pipes 475g extend from the right side between the second gaps, four heat pipes 475h extend from the right side between the third gaps, four heat pipes 475i extend from the right side between the fourth gaps, and four heat pipes 475j extend from the right side between the fifth gaps. In some embodiments, the heat pipes 475a and 475f extending from the left and right sides, respectively, may be the same component (i.e., a single heat pipe extending in both directions). The heat pipes may be configured to transfer heat from the windings 420 to a number of cooling fins 470a, 470b located on each side. As shown, each of the left and right sides includes eight cooling fins 470. The cooling fins 470 may provide increased surface area for cooling. In this embodiment, instead of or in addition to forcing air through the gaps between the windings 420, the cooling air is configured to be blown across the cooling fins 470 and the fins 428 of the laminated magnet core 422.

1 and 3, where _e1 , _e2 , e3 are voltages driven by amplifiers to control the three respective currents _i1 , _i2 , _i3 and therefore the force output of the motor. Inductors _L11 , _L22 , _L33 are in series with the resistance R of each phase.

Using the three-phase motor of the linear motor 100, the acceleration of the moving part can be defined as follows:
m×"(t)=-k×(t)-bx'(t)+NBL ₁ i ₁ (t)+NBL ₂ i ₂ (t)+NBL ₃ i ₃ (t)-mg
where m is the mass of the moving part , x″(t) is the acceleration of the moving part , k is the spring constant of the system (related to the spring constant of the test material to which the moving part is connected, or zero if the moving part is not connected to the test material), b is the damping constant, x(t) is the position of the moving part , x′(t) is the velocity of the moving part , an array of motor force/back EMF constants, each 120° apart for each phase, and i is the current in each of phases a, b, and c.
The voltage on the first leg can be defined as:
_e1 (t)= _L11i'1 ( _{t )+L12i'2(t)+L13i'3} ⁽ _{t )} ⁺ _{R1i1 ( t} ⁾ +x'(t) _NBL1
where e1[t] is the voltage of the first phase, _L11 is the inductance in the first phase induced by the first phase inductor, _L12 is the inductance in the first phase induced by the second phase inductor, _L13 is the inductance in the first phase induced by the third phase inductor, _i1 '(t), _i2 (t), and _i3 (t) are the changes in current in phases a, b, c, and R is the resistance of each individual phase. Similarly, the voltages in the second and third legs can be defined as follows:
_e2 (t) = _L21i1 ^' (t ₎ + _{L22i2 '} (t) + _L23i3 ^{' (} t ₎ + _R2i2 ( _t ) + x'(t) _NBL2
e3 (t) = _L31i1 ^' (t ₎ + _{L32i2 '} (t ₎ + _L33i3 ^{' (} t ₎ + _R3i3 (t) + x'(t) _NBL3
As long as there is movement in the moving part , even if the voltages on the three legs ( _e1 (t), _e2 (t), _e3 (t)) are cut to zero, the x'(t)NBL terms in each voltage equation will not become zero because the moving part is moving. This shows that EMFs are generated by these x'(t)NBL terms, which result in a force resisting the current change and therefore its motion according to the acceleration equation. Thus, the three phase motor, and the movement of the moving part , is configured to generate a damping force that further slows down the movement of the moving part in addition to the eddy current magnet system described herein above, when the current in each phase is cut or shorted.

Thus, embodiments of the present invention may include a suspension system that supports the range of motion of the moving parts without physically touching the moving parts and without sliding therebetween and/or without rolling friction. For example, the suspension system may be configured to facilitate the movement of the moving parts in one dimension relative to the stator assembly without physically touching the moving parts . In one embodiment or implementation, an air bushing may provide, support, or otherwise facilitate the range of motion of the moving parts (stroke length) in one dimension (back and forth along a single axis of motion) without the suspension system being mechanically or structurally connected, attached, or touching the moving parts during operation. The suspension system may be configured to limit, or at least substantially limit, the movement of the moving parts in this one dimension or along this one axis of motion (if the air bushing is compliant and allows a very small degree of compliance in another dimension).

In an exemplary embodiment, the absence of mechanical or structural connection prevents contact friction between the suspension system and the moving part during operation or movement, which may be provided by an air gap located between an air bushing of the suspension system and an air bushing shaft of the moving part . The suspension system contemplated herein creates a support system for maintaining precise motion of the moving part without structural contact or connection along a single dimension or single axis of movement. The suspension system contemplated herein may thereby be considered to be in indirect mechanical communication (e.g., via an air gap) with the moving part during operation and movement.

Methods of operating a linear motor and/or material testing device or system are also contemplated. For example, contemplated methods include providing a linear motor having a multi-phase stator assembly, a moving part proximate the multi-phase stator assembly, and a suspension system. The method includes receiving power by the multi-phase stator assembly, moving the moving part back and forth along a movement axis after receiving power by the multi-phase stator assembly, and supporting the moving part with the suspension system by controlling the movement of the moving part relative to the multi-phase stator assembly such that there is no sliding or rolling contact between the moving part and the suspension system. The method includes utilizing a three-phase linear motor and a stator assembly to create a magnetic field that moves a magnetic moving part . The method may include moving the moving part back and forth along the movement axis with a stroke length greater than 70 mm, 80 mm, 90 mm, or 100 mm along the movement axis. Contemplated methods include arranging poles in the stator such that the phases alternate in an A-B-C-A-B-C relationship.

A further contemplated method includes providing a stator assembly, a moving part proximate the stator assembly having an array of flat magnets disposed thereon, and a suspension system. The contemplated method includes receiving electrical power by the stator assembly, exposing the array of flat magnets to a magnetic field generated by the stator assembly, generating a back and forth motion in the moving part by the array of flat magnets, and supporting the moving part with the suspension system by controlling the movement of the moving part relative to the multi-phase stator assembly such that there is no sliding or rolling contact between the moving part and the suspension system. The method may further include skewing the flat magnets in the array of flat magnets at a skew angle of between 0.5 degrees and 5 degrees.

Further contemplated methods include providing a stator assembly, a moving part proximate the stator assembly, and a suspension system. The method includes receiving power by the stator assembly, moving the moving part back and forth along the axis of movement after receiving power by the stator assembly, and supporting the moving part on the suspension system without physically touching the moving part by the suspension system during movement. The method includes allowing the moving part to move relative to the suspension system without sliding or rolling contact between the moving part and the suspension system and without a structural connection between the moving part and the stator assembly by the suspension system. The method may further include providing at least one air bushing to the suspension system. The method may include allowing the moving part to move relative to the suspension system without sliding or rolling contact between the moving part and the suspension system by the air bushing. The method using the air bushing may include using recycled air from the air bushing to cool components of the linear motor, such as the stator assembly and its magnets.

The envisaged method further comprises providing a stator assembly, a moving part adjacent to the stator assembly, a suspension system and a magnetic damping system. The method comprises receiving power by the stator assembly, moving the moving part back and forth along the axis of movement after receiving power by the stator assembly, supporting the moving part with the suspension system by controlling the movement of the moving part relative to the stator assembly such that there is no sliding contact or rolling between the moving part and the suspension system, disconnecting the power to the stator assembly, and absorbing the kinetic energy of the movement of the moving part by the magnetic damping system when the power to the linear motor is disconnected. If the damping method uses a multi-phase linear motor such as a three-phase linear motor, the method may comprise simultaneously disconnecting the power to each of the phases and using the generated eddy current to damp the movement of the moving part . The method further comprises using the movement of the moving part between the coils of the system to generate a current and therefore a force that resists the movement of the moving part .

While embodiments of the present invention have been described herein for purposes of illustration, many modifications and changes will become apparent to those skilled in the art. It is therefore intended by the appended claims to cover all such modifications and changes that fall within the true spirit and scope of the invention.

The description of the various embodiments of the present invention has been presented for illustrative purposes, but is not intended to be exhaustive or limited to the disclosed embodiments. For example, the absence of any mechanical connection and attachment between the suspension system 300 and the moving part 200 in the embodiments described herein is a key inventive concept to some embodiments of the present invention described herein, but other inventive embodiments may be capable of incorporating other aspects of the inventive concepts described herein with a connected or attached suspension system as taught in U.S. Pat. No. 6,405,599. For example, embodiments of the present invention may utilize a multi-phase or three-phase linear motor, flat magnet array moving part and/or damping system as described herein, along with an attached flexure component suspension system as described in U.S. Pat. No. 6,405,599. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terms used herein are selected to best explain the principles of the embodiments, practical applications or technical improvements to the technology found in the market, or to enable those skilled in the art to understand the embodiments disclosed herein.

Claims (20)

A test apparatus comprising:
a linear motor including a stator assembly and a moving portion , the moving portion being mechanically coupleable to a test body configured to move relative to the stator assembly by operation of the linear motor;
a suspension system configured to facilitate movement of the moving part relative to the stator assembly along an axis perpendicular to the movement without physically touching the moving part during its movement, the suspension system including at least one vertically arranged air bushing configured to enable vertical movement of the moving part relative to the suspension system without sliding or rolling contact between the moving part and the suspension system;
the linear motor and the suspension system are configured to provide frictionless suspension of the moving part and vertical movement of the moving part ;
Test equipment. The testing device of claim 1 , wherein at least one air bushing is disposed within an opening in the suspension system. the suspension system includes a frame body having a first opening extending along a first axis parallel to the axis of movement;
the at least one air bushing is located within the first opening;
The testing device of claim 2 , wherein the moving portion includes a first air bushing shaft extending into the first opening. The test apparatus of claim 3, wherein the at least one air bushing includes a first air bushing located adjacent to a first end of the first opening and a second air bushing located adjacent to a second end of the first opening. the frame body includes a second opening extending along a second axis parallel to the axis of movement;
the moving portion includes a second air bushing shaft extending into the second opening;
5. The testing apparatus of claim 4, wherein the second opening includes a third air bushing located proximate a first end of the second opening and a fourth air bushing located proximate a second end of the second opening. The test apparatus of claim 3, wherein the at least one air bushing is mounted in the first opening of the frame body in a flexible manner such that some movement between the air bushing and the frame body is permitted. The test apparatus of claim 3, wherein the at least one air bushing is removably mounted within the first opening of the frame body with an interference fit. The test apparatus of claim 7, wherein the at least one air bushing has a hollow cylindrical shape and the first air bushing shaft is a cylindrical shaft having a radius 3 to 5 microns smaller than the inner radius of the at least one air bushing. the stator assembly includes a first coil subassembly and a second coil subassembly;
the moving part is disposed and extends between the first coil subassembly and the second coil subassembly, the moving part including a magnet frame having a plurality of permanent magnets disposed thereon;
the first air bushing shaft extends parallel to the magnet frame;
a top end plate and a bottom end plate disposed on the top and bottom sides of the magnet frame connect the first and second air bushing shafts to the magnet frame such that a first space extends parallel to a movement axis between the first air bushing shaft and the magnet frame, and a second space extends parallel to the movement axis between the second air bushing shaft and the magnet frame;
6. The test apparatus of claim 5, further comprising a duct system configured to use air flow through at least one air bushing in cooling at least one of the first coil subassembly, the second coil subassembly, and the moving part coil. The testing apparatus of claim 9 , wherein the travel portion includes a specimen shaft extending from at least one of the top end plate and the bottom end plate, and a fifth air bushing encircling the specimen shaft. A linear motor,
a stator assembly configured to receive electrical power;
a moving part adjacent to the stator assembly and configured to move relative to the stator assembly when the stator assembly receives power;
a suspension system configured to facilitate movement of the moving part relative to the stator assembly along an axis perpendicular to the movement without physically touching the moving part during its movement, the suspension system including at least one vertically arranged air bushing configured to enable vertical movement of the moving part relative to the suspension system without sliding or rolling contact between the moving part and the suspension system ;
the linear motor and the suspension system are configured to provide frictionless suspension of the moving part and vertical movement of the moving part ;
Linear motor. 12. The linear motor of claim 11, wherein at least one air bushing is disposed within an opening in the suspension system. the suspension system includes a frame body having a first opening extending along a first axis parallel to the axis of movement;
the at least one air bushing is located within the first opening;
The linear motor of claim 12 , wherein the moving portion includes a first air bushing shaft that extends into the first opening. The linear motor of claim 13, wherein the at least one air bushing includes a first air bushing located adjacent to a first end of the first opening and a second air bushing located adjacent to a second end of the first opening. the frame body includes a second opening extending along a second axis parallel to the axis of movement;
the moving portion includes a second air bushing shaft extending into the second opening;
15. The linear motor of claim 14, wherein the second opening includes a third air bushing located proximate a first end of the second opening and a fourth air bushing located proximate a second end of the second opening. The linear motor of claim 13, wherein the at least one air bushing is mounted within the first opening of the frame body in a flexible manner such that some movement between the air bushing and the frame body is permitted. The linear motor of claim 13, wherein the at least one air bushing is removably mounted within the first opening of the frame body with an interference fit. The linear motor of claim 17, wherein the at least one air bushing has a hollow cylindrical shape and the first air bushing shaft is a cylindrical shaft having a radius 3 to 5 microns smaller than the inner radius of the at least one air bushing. the stator assembly includes a first coil subassembly and a second coil subassembly;
the moving part is disposed and extends between the first coil subassembly and the second coil subassembly, the moving part including a magnet frame having a plurality of permanent magnets disposed thereon;
the first air bushing shaft extends parallel to the magnet frame;
a top end plate and a bottom end plate connect the first and second air bushing shafts to the magnet frame such that a first space extends parallel to a movement axis between the first air bushing shaft and the magnet frame, and a second space extends parallel to a movement axis between the second air bushing shaft and the magnet frame;
16. The linear motor of claim 15, further comprising a duct system configured to use air flow through at least one air bushing in cooling at least one of the first coil subassembly, the second coil subassembly, and a coil of the moving part . 1. A method comprising:
providing a stator assembly, a moving part adjacent to the stator assembly, and a suspension system, the suspension system including at least one vertically disposed air bushing configured to allow vertical movement of the moving part relative to the suspension system without sliding or rolling contact between the moving part and the suspension system;
receiving electrical power by the stator assembly;
moving the moving part back and forth along an axis perpendicular to the movement of the moving part relative to the stator assembly after receiving power by the stator assembly;
supporting the linear motor and suspension system in a frictionless manner;
supporting the moving part with the suspension system without physically touching the moving part during movement of the moving part and without sliding or rolling contact between the moving part and the suspension system .